Native Instruments Audio2 DJ interface and Linux 4 channel alsa config

I was recently given a Native Instruments Audio2 DJ interface, this is a great little card with working Linux drivers that works well with MIXXX using a variation of the .asoundrc available on the MIXXX site and other locations.

But either my version of the card, or the Linux driver has changed, as my card identifies differently so the config files available elsewhere don’t work with my OS (Xubuntu 14.04 with kernel 4.2.0-18-lowlatency).

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multiple audio outputs for cue with Mixvibes CrossDJ with Android Marshmallow

TLDR: If you can’t get multichannel USB audio working with CrossDJ on Android 6+, editing the /system/etc/audio_policy.conf file might help, if your device is rooted, and you don’t care about your warranty.

read on for how to do it, if you are comfortable with Linux shell commands and throwing your warranty to the wind. This is an updated version of a post I made to the Mixvibes support forum that they got a bit nervous about and locked…
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MIXXX DJ software – ZOG preferred build

I’m just documenting this here for reference, and perhaps others find this useful.

  • MIXXX is my preferred DJ software, it works well with the Numark Mixtrack Pro interface
  • One reason to go the digital DJ route is to maximise sound quality, this means FLAC files where possible, CD rips or purchased as wav from beatport, bleep.com or bandcamp.. and 320k mp3 when FLAC files are simply not available..
  • But I found the MIXXX 2.0 series (or earlier) had issues decoding some valid flac files purchased from bandcamp.com, causing sound to abruptly cut out, while MIXXX appears to continue playing
  • after discussing with the incredibly helpful MIXXX developers they pointed me to the MIXXX 2.1 alpha source code available on github, which uses a new audio decoding engine.
  • This fixed all my issues and has proven to be very stable. The effects I have found not that great, but I don’t use them much, sticking to relatively straight forward mixing.

So here are the steps….
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Roland SH-101 T1 Terminated!

Found a broken Roland SH-101 on Gumtree. Couldn’t believe my luck!
I was hoping for a simple fix, maybe a dodgy power switch or something. When I started to investigate it soon became apparent that someone had been there before me. The T1 transformer, which does DC-DC conversion from the 9VDC plug pack to the various analogue stages was missing! Also, the surrounding components had been lifted out of there solder pads. This wasn’t going to be a quick fix!

T1 Terminated!

Searching around the net and it was becoming obvious that this problem was fairly common but with no one having fixed it! Also, the T1 transformer is not available for purchase anywhere. Continue reading

MiniDSP chassis done, at last

Not strictly related to the speakers themselves, but as the miniDSP is a core component in driving the speakers I’ve noted this in the “beyond-econowave” posts:
For a long time the miniDSP was sitting bolted to a lump of wood, the “temporary” test chassis, with a cardboard box sitting on top of it to cover it. But this test chassis was quite noisy.

I’ve made a simple pine enclosure that makes up in solidity what it lacks in sophistication. It still containes the miniDSP and 2 simple OPA2134 based pre-amps to give me a bit of gain over the quiet miniDSP output, but I’ve got a 4 channel stepped attenuator (actually two stereo stepped attenuators ganged together) as a master volume, plus the software volume control as a fine volume pot.

There’s also a switch to switch over to the analogue input for “guest devices” .e.g. mates dropping over with DJ mixers or synths – so the sockets are on the front for easy access.
Made with bits of pine from the local hardware warehouse, and painted with leftover stain/varnish from my big speakers so it matches.
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ZOG low budget battery powered party blaster system

This system was started off cobbling together assorted spare parts that were in the garage gathering dust, to create a small battery powered (and partially solar) system that can fit in the boot of the car and be moved on a small trolley. But of course then I added some extra bits as well to get it how I liked it, so it’s not really assembled from “junk” any more, but it is all inexpensive low power use.

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addition of wooden compression driver stands that hide the protection circuit.

With the woofer enclosures now looking pretty good it was time to tidy up how the compression driver is supported, and tidy away the LPAD and protection circuitry.
I got some small pine boxes of the right size (from ETSY seller HIPROGRESS. I stained this the same colour as the speaker boxes, and got some self adhesive 4.5mm neoprene sheet from Clark Rubber to act as vibration damping, and protect the finish. This acts as a nice firm bed for the compression driver.

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some experimentations with ACD (ActiveCrossoverDesigner) & MiniDSP

Both before and after I went overseas I’ve been experimenting with the most excellent Active Crossover Designer spreadsheets by Charlie Laub, with a lot of input and information from the Stereo.net.Au forum users, especially henry218. It’s a lot of fun to upload some measurements and get some crossover configs and ideas from helpful people and find they work! Later I’ve gotten to grips myself with cutting and pasting miniDSP biquad settings. There is quite a bit of info posted in the relevant thread, but this remains a work in progress while I improve the measurements needed to get the best results.

Also I’m quite curious to see the improved ACD that Charli Laub has in development that will include heatmap graph capability for evaluating directivity.